Hello,
I'm wondering if my LT1 needs a new oil pump. My oil pressure gauge reads about 45 at cold idle, and 50 at cold driving. When at 180*, the idle pressure drops to about 15. Warm driving is about 40. My gauge doesn't bounce all around at idle so I believe my gauge is ok. My engine has about 140k on it.

Thoughts?

 

Sounds OK to me. What oil you using?

 

Mobil 1 (5w-30)?

The reason I question the '5W-30' Is because I had my dealer change the oil last time and I just told them to use the longest lasting mobil 1.

 

This readout off the stock gauge?
.
And yeah, sounds ok, but if worried, check with a mechanical gauge
.
Sent from my EVO 4G using Tapatalk

 

Yes I am reading the gauge from the dash.

 

That pressure sounds pretty good,especially for having 140k on it..

 

nice

 

The manual calls for 5w-30 - no problem there.

 

I thought that loss of oil pressure was caused by increased tolerances from bearing wear. It is my understanding that oil pumps rarely fail and cause a low oil pressure condition.

Maybe someone can clarify?

 

Also remember that the oil's viscosity raises as it becomes hotter

 

Viscosity drops as oil heats up. Its thick when its cold, thin when its hot.

From the Exxon/Mobil website:


Mobil 1 5W-30

SAE Grade 5W-30

Viscosity @ 100ºC, cSt (ASTM D445) 11.0

Viscosity, @ 40ºC, cSt (ASTM D445) 61.7

 

Presumed loss of oil pressure can come from an old sensor. They often indicate lower pressures as they age and as they get hot.

 

Sorry, that's what I meant

 

I often hear a lot of people talk about replacing pumps but being mechanical gear driven pumps I don't see how they can go bad so easily.

I spun a rod bearing so I disassembled the pump to clean out any shavings that may be in there, and replaced the nylon with a steel sleeve.

My oil pressure has been fine, although I will mention that my nylon sleeve was broken when I dropped the oil pan.

I've read that the sleeve breaking is common and can result in a slight loss of pressure but I am not sure how true that is.